Such cartridges are often used for applying resins, sealing compounds or thermal and/or sound insulation compounds.
The sliding of the end wall of the cartridge is brought about by a piston which is operated directly by hand or, more commonly, which is an integral part of a manual operating appliance, in the form of a gun, and generally with a rack or friction advance.
Some products consist of several components which must be mixed, in given proportions, only at the time of application.
It has therefore already been proposed to store these products in multiple-casing cartridges, with an outer casing and at least one internal casing, a first component being stored between the outer casing and the inner casing and a second component inside the inner casing.
FR-A-81 04213 gives details of such a double-casing cartridge. In order to maintain the relative axial position of the two casings, the viscosities of the two components not being identical, and in order to ensure the concentric arrangement of the front openings of the two casings, as well as the channelling of the component from the outer casing to the application end piece, provision is made, on the end piece side, for a spacing and connecting piece and, on the end walls side, a rear stop dish.
The present invention first aims to dispense with this spacing piece and this rear stop.
DE-A-3 301 388 also teaches a tubular cartridge for storing and applying a non-solid product having a multiple casing comprising an outer casing with a front end piece for receiving an application nozzle and an annular rear thrust wall mounted slidingly in the outer casing, and at least one inner casing with a front end piece and a disc-shaped rear thrust wall, means for connecting the two outer and inner casings being provided for ensuring their mutual locking in axial and radial positions.
But the front end piece of the inner casing of this reference does not extend inside the front end piece of the outer casing. Thus, the cartridge of this reference cannot solve the problem of applying several components to be mixed only upon application and in given proportions.
The present invention thus relates to a tubular cartridge for storing and applying a non-solid product, of this last type, characterized by the fact that the front end piece of the inner casing extends inside the front end piece of the outer casing and the means of connection comprise, on one of the two casings, at least one snap-on rib, with a front portion for snapping on and rear locking and a rear portion for front locking and, on the other one of the two casings, two shoulders arranged to interact respectively with the two front and rear portions of the rib.
The invention offers the advantage of particularly simple production and assembly of the multiple-casing cartridge. FR-A-79 10957 also discloses details of a multiple-casing cartridge which is also provided, on the inner casing, with radial bracing ribs or fins preventing the inner casing from moving forwards, that is to say towards the end piece of the outer casing, and ensuring the mutual locking of the two casings in the radial position. However, these fins do not prevent the inner casing from moving towards the rear. Moreover the cartridge is described, in this document FR-A-79 10957, with a rear stop. With this removed, the risk of a backward movement of the inner casing can therefore exist.